Paralympic innovation: 'bum brakes', blades and wind tunnels

The Paralympic Games not only demonstrate human fitness and
endurance, but also engineering prowess, with many athletes
requiring bespoke prosthetics and equipment to help them perform.
Wired.co.uk takes a look at some of the technologies used in the
Games.

Wheelchairs
Paralympic wheelchairs are engineered for their specific sport,
with wheel angle, sitting position and accessories all tuned for
optimal performance -- much like bicycles.

In basketball, each of team GB's wheelchairs were individually moulded for each player, taking into account a
player's size, shape and particular disability. Team members
underwent 3D scans at Loughborough University to capture their
bodies' biomechanical movements and their positions in their
existing wheelchairs. Seats were then optimised using
computer-aided design and then 3D printed. This technique helped
reduce the weight of wheelchairs by around a kilo and achieve
improvements in speed, acceleration and
manoeuverability. Track wheelchairs need to be light and
extremely rigid to make sure that the maximum amount of the
athlete's power is transferred to the track. As such they are
made with aerospace-graded aluminium tubes.

A number of track athletes -- such as Shelly Woods -- tested
their wheelchairs in BAE Systems' wind tunnel, keeping airflow speeds to 45kmph,
rather than the Mach2 speeds used to test jets. Tests revealed that
subtle changes in the athlete's positioning in the chair including
the placement of their hands would reduce drag by up to 10
percent.

Blades Olympian and Paralympian runner Oscar "Blade Runner"
Pistorius is probably the best-known disabled athlete in the world.
He uses prosthetic running blades, which are produced by a number
of different companies including Otto Bock. The company
combines a customised socket liner and prosthesis with a flexible
blade, made by building up more than 80 layers of carbon fibre. The
blades feature spikes just like running shoes.

The blades currently being used don't give Paralympic runners
the same amount of energy that able-bodied runners get from their
legs. They return around 90 percent of the energy stored, much less
than the 250 percent return achieved by a real leg. The athletes
can only use the power from their hamstrings or hip flexor muscles,
and don't have the additional energy a regular runner might get
from their thigh, calf and ankle.

Bikes
Canadian cyclist Jaye Milley is classified as a quadruple amputee, having been
born with underdeveloped arms and legs. The only one of his limbs
not attached to his highly modified Cervelo bike by a prosthetic is
half of his right hand. Lacking the hand-power to squeeze a
handlebar brake, Milley's bike features a "bum brake", whereby he
shifts his weight back to slow down. Milley slides the upper part
of he left arm into a prosthetic attached to the handlebar (he
lacks a forearm or hand). As Milley has no feet nor shin
bones, he has two prosthetic racing legs with built in cleats that
attach straight to the peddles.

For competitors with no legs at all, there is also the handbike.
Italy's Alex Zanardi was a Formula One driver until he had a crash
in 2001 that cost him both of his legs. He is now cycling in the
Paralympics on a three-wheeled hand bike, where the arms are used
to rotate cycle pedals.

Discus throwing frame Throwing the discus produces a tremendous amount of
energy and pressure on the frame of their seat. Former serviceman
Derek Derenalagi lost his legs in Afghanistan in 2007 and has since
trained as a discus thrower and a shot putter. He worked with a
charity called Remap to develop a one-off piece of equipment to suit his
needs. The throwing frame consists of a strong, lightweight frame
that is secured to the ground, with a seat and two belts to strap
him in.

Archery
Depending on the level of
disability, Paralympic archers can use a number of different
devices. These include a wheelchair bow slinger, where a pole is
mounted into the ground near the archer's stand to allow the archer
to string the bow independently. Archers with below-elbow
amputations can use a prosthesis with hook fingers. However, one
armless archer -- the USA's Matt Stutzman -- doesn't bother: he has
perfected a technique of holding and aiming the bow using only his
feet.

Comments

"The blades currently being used don't give Paralympic runners the same amount of energy that able-bodied runners get from their legs. They return around 90 percent of the energy stored, much less than the 250 percent return achieved by a real leg. The athletes can only use the power from their hamstrings or hip flexor muscles, and don't have the additional energy a regular runner might get from their thigh, calf and ankle."

You protest too much. The 'blade runners' also don't have to swing kilos of meat and bone around on their furthest extremities. They don't even have to waste energy to keep those cells alive.

Time is only one way to measure a sprinter's performance. When you look at what the rest of Oscar Pistorius's body is doing in terms of e.g. processing oxygen, it is clear that he could not make the grade as an olympic sprinter (had he the full compliment of body parts).

What these paralympians do is inspiring, but blades are a huge performance boost.